<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="UTF-8" />
		<meta http-equiv="X-UA-Compatible" content="IE=edge" />
		<meta name="viewport" content="width=device-width, initial-scale=1.0" />
		<title>Document</title>
		<style>
			.content {
				width: 1100px;
				margin: 0 auto;
				height: 800px;
				background-color: yellow;
			}
			.item {
				width: 221px;
				height: 168px;
				background-color: blue;
				float: left;
				border: 1px solid #000;
				box-sizing: border-box;
				/* 后面的元素会盖在前面的元素上 */
				/* margin-left: -1px; */

				margin-right: -1px;
			}

			.box {
				/* margin-left: 1px; */
			}
			.item.first {
				width: 220px;
			}

			.container {
				display: flex;
				background-color: #00f;
			}
			.demo {
				width: 100px;
				height: 100px;
			}
			.demo1 {
				background-color: #f00;
				margin-right: -10px;
			}
			.demo2 {
				background-color: #0f0;
			}
		</style>
	</head>
	<body>
		<div class="content">
			<div class="box">
				<div class="item first">1</div>
				<div class="item">2</div>
				<div class="item">3</div>
				<div class="item">4</div>
				<div class="item">5</div>
			</div>
		</div>

		<div class="container">
			<div class="demo demo1"></div>
			<div class="demo demo2"></div>
		</div>
	</body>
</html>
